U.S. patent number 5,364,388 [Application Number 07/944,431] was granted by the patent office on 1994-11-15 for beam delivery system for corneal surgery.
Invention is credited to Jeffrey E. Koziol.
United States Patent |
5,364,388 |
Koziol |
* November 15, 1994 |
Beam delivery system for corneal surgery
Abstract
An apparatus and method for delivering radiant energy beams onto
an area of a cornea in a line focus to create a linear incisions.
The radiant energy beams may be focused in a linear configuration
onto the external surface of the cornea or onto intrastromal areas
of the cornea of an eye to ablate the cornea in a radial slot,
circumferential curved slot, or lenticular pattern, and thereby
modify its curvature and refractive power. The apparatus includes
an array of central reflectors and an assembly of peripheral
reflectors. Each central reflector is associated with a respective
peripheral reflector so that a beam reflected by the central
reflector is intercepted by its associated peripheral reflector and
is again reflected to precisely incise either external or internal
areas of the cornea. Each peripheral reflector has a curved
reflective surface to provide a line focus on the cornea, including
both rectilinear and curvilinear line focus to create radial and
circumferential curved incisions. In a modified embodiment, the
assembly of peripheral reflectors and the array of central
reflectors rotate to permit lathing of the cornea.
Inventors: |
Koziol; Jeffrey E. (Arlington
Heights, IL) |
[*] Notice: |
The portion of the term of this patent
subsequent to December 24, 2008 has been disclaimed. |
Family
ID: |
27390719 |
Appl.
No.: |
07/944,431 |
Filed: |
September 14, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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812163 |
Dec 23, 1992 |
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598793 |
Oct 17, 1990 |
5074859 |
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464637 |
Jan 5, 1990 |
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176765 |
Apr 1, 1988 |
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Current U.S.
Class: |
606/5; 606/10;
606/13 |
Current CPC
Class: |
A61F
9/00804 (20130101); A61F 2009/00853 (20130101); A61F
2009/00872 (20130101) |
Current International
Class: |
A61F
9/01 (20060101); A61F 9/007 (20060101); A61N
005/02 () |
Field of
Search: |
;606/3-6,10-13,19 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2594686 |
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Aug 1987 |
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FR |
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8707165 |
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Dec 1987 |
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WO |
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Other References
"Excimer Laser Ablation of Cornea and Lens", Puliafito et al,
Ophthalmology, vol. 92, No. 9, Jun. 1985, pp. 741-748. .
"Corneal Surgery", Girard, vol. 2, 1981, pp. 106-171. .
"Response of the Corneal Epithelium to KrF Excimer Laser Pulses",
J. Taboda et al, Health Physics, vol. 40, May 1981, pp.
677-683..
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Primary Examiner: Shay; David M.
Attorney, Agent or Firm: Roylance, Abrams, Berdo &
Goodman
Parent Case Text
RELATED APPLICATIONS
This is a continuation-in-part application of Ser. No. 07/812,163
filed on Dec. 23, 1992, which is a continuation of Ser. No.
07/598,793 filed on Oct. 17, 1990, now U.S. Pat. No. 5,074,859,
which is a continuation of Ser. No. 07/464,637 filed on Jan. 5,
1990, now abandoned, which is a continuation of Ser. No. 07/176,765
filed on Apr. 1, 1988, now abandoned.
Claims
What is claimed is:
1. An apparatus for delivering radiant energy beams onto an area of
a cornea of an eye centered on a main optical axis, the combination
comprising:
a source of radiant energy beam aimed along the main optical
axis;
a support;
an array of discrete central reflector means, arranged about the
main optical axis, for intercepting the radiant energy beam
incident thereon, splitting the beam into a plurality of beam
portions, and reflecting each beam portion outwardly of the main
optical axis;
first means, coupled to said support and said array of central
reflector means, for coupling said central reflector means to said
support;
an assembly of discrete peripheral reflector means, outwardly
spaced from said central reflector means, each peripheral reflector
means for intercepting one of said reflected beam portions from an
associated central reflector means and for directing said
intercepted beam portion generally along the main optical axis and
for incidence onto an area of the cornea; and
second means, coupled to said support and said peripheral reflector
means, for coupling said peripheral reflector means to said
support,
each of said peripheral reflector means including means for
focusing said intercepted beam portion onto an area of the cornea
separate and discrete from the incidence of remaining said
intercepted beam portions reflected onto areas of the cornea and in
a linear configuration.
2. An apparatus according to claim 1, wherein
said second means comprises means for supporting said array of
central reflector means for angular movement relative to said
assembly of peripheral reflector means.
3. An apparatus according to claim 1, wherein
said first and second means comprises means, coupled to said array
of central reflector means and said assembly of peripheral
reflector means, for fixedly interconnecting said array and said
assembly, and means for rotatably supporting said interconnected
array and assembly on said support for rotation about the main
optical axis, and
means for rotating said interconnected array and assembly.
4. An apparatus according to claim 1, wherein
said central reflector means are mirrors.
5. An apparatus according to claim 1, wherein
said peripheral reflector means are mirrors.
6. An apparatus according to claim 1, wherein
said central reflector means have flat reflective surfaces.
7. An apparatus according to claim 1, wherein
each of said means for focusing comprises a curved reflective
surface.
8. An apparatus according to claim 1, wherein
each of said means for focusing comprises a substantially
semi-cylindrical reflective surface.
9. An apparatus according to claim 1, wherein
each of said means for focusing comprises a reflective surface that
is curved about an axis A and is curved about an axis B which is
perpendicular to axis A.
10. An apparatus according to claim 1, wherein
each of said means for focusing comprises a reflective surface that
is curved about an axis A, and having a radius of curvature varying
therealong.
11. An apparatus according to claim 1, and further comprising
said peripheral reflector means are holographic elements.
12. An apparatus according to claim 1, wherein
said array of central reflector means includes from two to eight
central reflector means, and
said assembly of peripheral reflector means includes from two to
eight peripheral reflector means.
13. An apparatus according to claim 1, wherein
said array of central reflector means is an octagonal array.
14. An apparatus according to claim 1, and further comprising
means, coupled to said support, for reflecting a part of the beams
reflected by said peripheral reflector means and determining the
length of the beams from the source and the energy distribution of
the beams.
15. An apparatus according to claim 1, and further comprising
an eye positioning device coupled to said support for positioning
the cornea relative to said central reflector means.
16. An apparatus according to claim 15, and further comprising
conduit means coupled to said eye positioning device for delivering
fluid to the cornea.
17. An apparatus according to claim 1, wherein
each of said means for focusing is configured to focus said
intercepted beam portion onto an external area of the cornea for
ablating an external surface of the cornea.
18. An apparatus according to claim 17, wherein
said first and second means comprises means, coupled to said array
of central reflector means and said assembly of peripheral
reflector means, for fixedly interconnecting said array and said
assembly, and means for rotatably supporting said interconnected
array and assembly on said support for rotation about the main
optical axis, and
means for rotating said interconnected array and assembly.
19. An apparatus according to claim 17, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion in a rectilinear configuration on the
cornea.
20. An apparatus according to claim 19, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion along a line extending radially, outwardly
from the main optical axis of the cornea.
21. An apparatus according to claim 17, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion in a curvilinear configuration on the
cornea.
22. An apparatus according to claim 21, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion along a line extending radially, outwardly
from the main optical axis of the cornea.
23. An apparatus according to claim 22, wherein
said first and second means comprises means, coupled to said array
of central reflector means and said assembly of peripheral
reflector means, for fixedly interconnecting said array and said
assembly, and means for rotatably supporting said interconnected
array and assembly on said support for rotation about the main
optical axis, and
means for rotating said interconnected array and assembly.
24. An apparatus according to claim 21, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion along a circumferentially curved line on
the cornea.
25. An apparatus according to claim 24, wherein
said first and second means comprises means, coupled to said array
of central reflector means and said assembly of peripheral
reflector means, for fixedly interconnecting said array and said
assembly, and means for rotatably supporting said interconnected
array and assembly on said support for rotation about the main
optical axis, and
means for rotating said interconnected array and assembly.
26. An apparatus according to claim 1, wherein
each of said means for focusing is configured to focus said
intercepted beam portion onto an intrastromal area of the cornea
without ablating an external surface of the cornea.
27. An apparatus according to claim 26, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion in a rectilinear configuration onto the
intrastromal area of the cornea.
28. An apparatus according to claim 27, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion along a line extending radially, outwardly
from the main optical axis of the cornea.
29. An apparatus according to claim 28, wherein
said first and second means comprises means, coupled to said array
of central reflector means and said assembly of peripheral
reflector means, for fixedly interconnecting said array and said
assembly, and means for rotatably supporting said interconnected
array and assembly on said support for rotation about the main
optical axis, and
means for rotating said interconnected array and assembly.
30. An apparatus according to claim 26, wherein
each of said means for focusing is further configured to focus said
intercepted bee portion in a curvilinear configuration onto the
intrastromal area of the cornea.
31. An apparatus according to claim 30, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion along a line extending radially, outwardly
from the main optical axis of the cornea.
32. An apparatus according to claim 31, wherein
said first and second means comprises means, coupled to said array
of central reflector means and said assembly of peripheral
reflector means, for fixedly interconnecting said array and said
assembly, and means for rotatably supporting said interconnected
array and assembly on said support for rotation about the main
optical axis, and
means for rotating said interconnected array and assembly.
33. An apparatus according to claim 30, wherein
each of said means for focusing is further configured to focus said
intercepted beam portion along a circumferentially curved line onto
the intrastromal area of the cornea.
34. An apparatus according to claim 33, wherein
said first and second means comprises means, coupled to said array
of central reflector means and said assembly of peripheral
reflector means, for fixedly interconnecting said array and said
assembly, and means for rotatably supporting said interconnected
array and assembly on said support for rotation about the main
optical axis, and
means for rotating said interconnected array and assembly.
35. A method of ablating an area of a cornea via a radiant energy
beam, comprising the steps of
aligning a source of radiant energy beam and the cornea along a
main axis,
emitting the radiant energy beam from the source,
splitting the beam into a plurality of beam portions and reflecting
those beam portions outwardly of the main axis,
reflecting the outwardly directed beam portions generally along the
main axis to produce a plurality of output beam portions, and
directing and focusing each of the output beam portions for
incidence onto the cornea in an area separate and discrete from the
incidence of remaining output beam portions reflected onto areas of
the cornea and in a linear configuration.
36. A method according to claim 35, wherein
the directing and focusing step includes focusing the output beam
portions onto intrastromal areas of the cornea for ablating the
intrastromal areas without ablating an external surface of the
cornea.
37. A method according to claim 36, wherein
the directing and focusing step includes focusing the output beam
portions in a rectilinear configuration onto the intrastromal areas
of the cornea.
38. A method according to claim 37, wherein
the directing and focusing step includes focusing the output beam
portions along a line extending radially, outwardly from the main
optical axis of the cornea.
39. A method according to claim 38, wherein
the splitting, the two reflecting, and the directing and focusing
steps include the step of revolving the output beam portions about
the main optical axis of the cornea.
40. A method according to claim 36, wherein
the directing and focusing step includes focusing the output beam
portions in a curvilinear configuration onto the intrastromal areas
of the cornea.
41. A method according to claim 40, wherein
the directing and focusing step includes focusing the output beam
portions along a line extending radially, outwardly from the main
optical axis of the cornea.
42. A method according to claim 41, wherein
the splitting, the two reflecting, and the directing and focusing
steps include the step of revolving the output beam portions about
the main optical axis of the cornea.
43. A method according to claim 40, wherein
the directing and focusing step includes focusing the output beam
portions along a circumferential curved line onto the intrastromal
areas of the cornea.
44. A method according to claim 43, wherein
the splitting, the two reflecting, and the directing and focusing
steps include the step of revolving the output beam portions about
the main optical axis of the cornea.
45. A method according to claim 35, wherein
the directing and focusing step includes focusing the output beam
portions onto external areas of the cornea for ablating the
external areas of the cornea.
46. A method according to claim 45, wherein
the directing and focusing step includes focusing the output beam
portions in a rectilinear configuration on the cornea.
47. A method according to claim 46, wherein
the directing and focusing step includes focusing the output beam
portions along a line extending radially, outwardly from the main
optical axis of the cornea.
48. A method according to claim 47, wherein
the splitting, the two reflecting, and the directing and focusing
steps include the step of revolving the output beam portions about
the main optical axis of the cornea.
49. A method according to claim 45, wherein
the directing and focusing step includes focusing the output beam
portions in a curvilinear configuration on the cornea.
50. A method according to claim 49, wherein
the directing and focusing step includes focusing the output beam
portions along a line extending radially, outwardly from the main
optical axis of the cornea.
51. A method according to claim 50, wherein
the splitting, the two reflecting, and the directing and focusing
steps include the step of revolving the output beam portions about
the main optical axis of the cornea.
52. A method according to claim 49, wherein
the directing and focusing step includes focusing the output beam
portions along a circumferential curved line on the cornea.
53. A method according to claim 52, wherein the splitting, the two
reflecting, and the directing and focusing steps include the step
of revolving the output beam portions about the main optical axis
of the cornea.
Description
FIELD OF THE INVENTION
The invention relates to an apparatus for delivering radiant energy
beams onto the cornea of an eye. More specifically, the invention
relates to an array of central reflectors for intercepting a
radiant energy beam and reflecting and splitting the beam along
several paths to an assembly of peripheral reflectors radially
spaced therefrom, which in turn focus and reflect the beams onto
the cornea in line configurations. The central reflector array and
the peripheral reflector assembly can be rotated as a single unit
relative to the eye for scanning operations. The invention when
used in a stationary position can ablate the cornea via
simultaneously applied radial or circumferential incisions, and
when rotated can re-profile the cornea via photolathing.
BACKGROUND OF THE INVENTION
The use of high intensity light sources such as lasers for cutting
and reshaping eyes has expanded in recent years in part due to the
superior precision, controllability and safety which such cutting
technology offers over other cutting technologies, such as
mechanical cutting of the eye. One type of ophthalmic surgical
procedure for which high-intensity light radiation is particularly
well suited is the radial keratotomy procedure in which a number of
radial incisions are made on the cornea of the eye to change the
curvature of the cornea.
Several methods and apparatus for performing radial keratotomies
with lasers have been proposed. See, for example, U.S. Pat. No.
4,648,400 to Schneider et al; and U.S. Pat. No. 4,665,913 to
L'Esperance, Jr. Schneider et al describe the use of lasers to
selectively ablate the cornea of the eye by directing the laser
beam through a generally planar mask having radial slots. The
radial slots of the mask permit portions of the laser beam to pass
through the mask and incise the cornea in a pattern of
circumferentially spaced radial incisions.
Lasers have also been used to ablate an annular portion of the
cornea by scanning or variably attenuating the laser beam. Such
scanning changes the front surface of the cornea to a different
optical curvature, thereby changing the refraction of the eye. See,
for example, U.S. Pat. No. 4,669,466 to L'Esperance.
In such an application, it is desirable to deliver uniform beam
energy along the curved scanning path. However, since the cornea
presents a convexly curved surface to the laser beam, the outer
circumferential portions of the cornea lie at further distances
from the beam source than those portions at or near the center of
the cornea. Thus, the laser beam incidents the cornea with a
different angle along the cornea's constantly changing surface
which causes variation of the energy density of the laser beam in a
direction perpendicular to the corneal surface.
Using a mask to produce corneal incisions does not focus the beam
on the corneal surface but merely projects the beam toward the
surface.
Additionally, the energy of the laser beam may not be distributed
uniformly due to the position of the mask relative to the beam. A
non-uniform distribution of energy results in differing depths of
the radial incisions, leading to an improper restructuring of the
curvature of the cornea.
More recently, laser systems have been developed to ablate
intrastromal areas of a cornea without ablating or piecing the
external surface of the cornea. These laser systems focus the lower
beams as a spot on either external or intrastromal areas of the
cornea to be ablated. Thus, to create a linear incision, the laser
must ablate a plurality of spots along the line of incisions. An
example of a laser system employing spot focus ablation is
disclosed in U.S. Pat. No. 4,907,586 to Bille et al, which is
hereby incorporated herein by reference.
SUMMARY OF THE INVENTION
Accordingly, a primary object of the present invention is to
provide an apparatus and method for delivering radiant energy from
a radiant energy source in a line focus onto an area of the cornea
to create linear incisions, including rectilinear and curvilinear
incisions.
A further object of the invention is to provide an apparatus and
method which can simultaneously direct a number of radiant energy
beams onto an eye from a single source.
A further object of the invention is to provide an apparatus and
method which can direct radiant energy onto an eye so as to lathe
the eye and for a lenticular ablation.
An additional object of the invention is to provide an apparatus
and method for delivering radiant energy onto an eye which
minimizes the energy needed to incise the cornea to a desired depth
via focusing of the radiant energy.
Another object of the invention is to provide an apparatus and
method for controlling radiant energy to produce optical changes in
an eye and maintain substantially constant incision depth across
the incision
Another object of the invention is to provide an apparatus and
method of conducting corneal surgery via focusing laser light and
thus concentrate the laser energy 100 to 10,000 times to permit use
of low cost lasers such as a frequency modified YAG laser.
The foregoing objects are basically attained by providing an
apparatus for delivering radiant energy beams onto the cornea of an
eye centered on a main optical axis, the combination comprising a
source of a radiant energy beam aimed along the main optical axis;
a support; an array of discrete central reflectors arranged about
the main optical axis for intercepting the radiant energy beam
incident thereon, splitting the beam into a plurality of beam
portions, and reflecting each beam portion outwardly of the main
optical axis; a first member coupled to the support and the array
of central reflectors for coupling the central reflectors to the
support; an assembly of discrete peripheral reflectors outwardly
spaced from the central reflectors, each peripheral reflector
intercepts one of the reflected beam portions from an associated
central reflector and directs the intercepted beam portion
generally along the main optical axis and incident onto the cornea;
and a second member coupled to the support and the peripheral
reflectors for coupling the peripheral reflectors to the support,
each of the peripheral reflectors including a mechanism for
focusing the intercepted beam portion onto an area on the cornea
separate and discrete from the incidence of the other of the
intercepted beam portions on the cornea and in a linear
configuration.
The foregoing objects are also attained by providing a method of
ablating a cornea via a radiant energy beam comprising the steps of
aligning a source of a radiant energy beam and the cornea along a
main optical axis, emitting the radiant energy beam from the
source, splitting the beam into a plurality of beam portions and
reflecting those beam portions outwardly of the main optical axis,
and reflecting the outwardly directed beam portions to produce
output beam portions incident on the cornea.
Other objects, advantages and salient features of the invention
will become apparent from the following detailed description,
which, taken in conjunction with the annexed drawings, discloses
preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings which form a part of this original
disclosure,
FIG. 1 is a front plan view of the beam delivering apparatus of the
present invention, showing an array of central reflectors, each
having an associated peripheral reflector radially and axially
spaced from it;
FIG. 2 is a cross-sectional side view of the beam directing
apparatus of FIG. 1, taken along line 2--2 in FIG. 1 and showing
the apparatus aligned between a laser beam source and the cornea of
an eye;
FIG. 3 is a cross-sectional side view of a modification of the
apparatus of FIG. 1, having a gas conduit system for delivering gas
to the ablated surface of the eye, a cornea alignment receptacle
for positioning the cornea and a detection system for detecting the
beam power density distribution as well as a motive assembly to
rotate the reflectors;
FIG. 4 is a cross-sectional side view of another modification of
the apparatus of FIG. 1, showing a second gas conduit delivery
system for delivering gas to the cornea of the eye during rotation
of the reflectors;
FIG. 5 is a perspective view of a modified peripheral reflector for
use in the apparatus of FIG. 1, showing the change in the radius of
curvature of the reflector along its central axis A;
FIG. 6 is a schematic view of a cornea having radial incisions
produced by a laser bee source in conjunction with the apparatus of
FIGS. 1-3;
FIG. 7 is a schematic representation of a cornea having a
lenticular ablation after scanning the radiant energy bees directed
onto the cornea by the apparatus of FIG. 4;
FIG. 8 is a schematic view of a cornea having intrastromal radial
incisions produced by a laser beam source in conjunction with the
apparatus of FIGS. 1-3;
FIG. 9 is a cross-sectional side view of another modification of
the apparatus of FIG. 1, having modified peripheral reflectors for
ablating circumferentially curved lines either on the external
surface of the cornea, or on intrastromal areas of the cornea
without disturbing, coagulating or ablating the tissue between the
peripheral reflectors and the intrastromal areas to be ablated;
FIG. 10 is a schematic view of a cornea having circumferentially
curved incisions on the external surface of the cornea;
FIG. 11 is a schematic view of a cornea having circumferentially
curved incisions on intrastromal areas of the cornea; and
FIG. 12 is a schematic view of a cornea having wedge-shaped
ablations on the external surface of the cornea formed by focusing
and pivoting radial lines of radiant energy onto external areas of
the cornea.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
As seen in FIG. 1, a beam delivering apparatus 10 for focusing
beams of radiant energy in a linear configuration is illustrated in
accordance with a first embodiment of the present invention, and
basically includes an annular array of central reflectors 12a-h and
an annular assembly of peripheral reflectors 14a-h. Peripheral
reflectors 14a-h are rigidly coupled to a rim 16. As seen in FIG.
2, rim 16 is rigidly coupled to a hub 18 by radial spokes 19, axial
rods 20 and a ring 21. Central reflectors 12a-h are coupled to hub
18.
Beam delivering apparatus 10 is rotatably supported within a
support or frame 22 about a main optical axis 24 which passes
through the center of a cornea 26 of an eye. A laser beam source
30, such as a frequency modified YAG laser for ablating external
surface areas of the cornea or a frequency-doubled YAG laser for
ablating intrastromal areas of the cornea, is positioned to emit a
beam along axis 24 and against central reflectors 12a-h. These
reflectors split and reflect the beam onto peripheral reflectors
14a-h which then focus and reflect the split beams onto cornea
26.
Beams delivering apparatus 10 can be modified in a number of ways
to adapt it for use in particular types of ophthalmic surgery. For
example, beam delivering apparatus 10 can be modified to perform
radial keratotomy operations on the external surface of cornea 26
or on intrastromal areas of cornea 26.
Referring now more specifically to the construction and orientation
of central reflectors 12a-h and peripheral reflectors 14a-h for the
radial keratotomy operation, a number of equal sized central
reflectors 12a-h are provided and, preferably, the number of
central reflectors is an even number more than two and less than
16, such as eight. As shogun in FIG. 1, eight equally sized central
reflectors 12a-h are rigidly coupled to one another along their
sides in a octagonal array. As seen in FIG. 2, each central
reflector 12a-h is oriented to present a slanted, outwardly facing
flat surface to the beam emanating from beam source 30. The angle
of each surface is about 50.degree.-60.degree. to axis 24.
Each peripheral reflector 14a-h is associated with one of central
reflectors 12a-h and is oriented so that its reflective surface 15,
which is curved and preferably semi-cylindrical about central axis
A as seen in FIG. 2 and angled at about 40.degree.-50.degree. to
axis 24, intercepts the beam reflected radially, outwardly by its
associated central reflector. Axis A intersects main optical axis
24 at an acute angle of about 40.degree.-50.degree.. Additionally,
each peripheral reflector is oriented so as to reflect the
intercept beam axially and radially inward and to focus the beam
into line focus either onto the external surface of cornea 26 or
onto an intrastromal area of the cornea. The reflective surfaces of
the central and peripheral reflectors can be mirrors or other
reflective material. For example, the peripheral reflectors can be
replaced with holographic elements.
As schematically shown in FIG. 6, a number of radial incisions 17
are cut via photoablation in the external surface of cornea 26
during the radial keratotomy operation. Alternatively, a number of
radial, intrastromal incisions 17a can be cut via photoablation in
intrastromal areas of cornea 26 during a radial keratotomy
operation, as schematically illustrated in FIG. 8.
Beam delivering apparatus 10 can be used to produce the external or
intrastromal incisions simultaneously. As seen in FIG. 1, each
central reflector 12a-h intercepts the beam and reflects the beam
towards its associated peripheral reflector. Central reflectors
12a-h are preferably rotatably coupled to hub 18 via an axle 53
fitting into the hub 18 and a screw adjustment assembly including
three set screws 56 to lock the reflectors relative to hub 18.
Central reflectors 12a-h can be moved as a single unit relative to
hub 18 and the adjustment screws 56 can then be operated to adjust
and fix the relative position of the central reflectors relative to
the peripheral reflectors.
The combination of central and peripheral reflectors including the
rim 16, hub 18, spokes 19, rods 20 and ring 21 are supported for
rotation relative to frame 22 via ball bearing assembly 38, which
is coupled to the frame and to rim 16. Thus, the angular position
of the reflectors relative to the cornea and axis 24 can be varied.
This allows angular placement as desired of either external
incisions 17 on the cornea or intrastromal incisions 17a in the
cornea.
The operation of beam delivering apparatus 10 during a simple
radial keratotomy operation is as follows. Cornea 26 is immobilized
by appropriate means and laser beam source 30 is positioned to emit
a beam along main optical axis 24, which passes through the center
of cornea 26. Beam directing apparatus 10 is positioned between
beam source 30 and cornea 26 and is appropriately spaced from
cornea 26 so that the beams reflected by the central and peripheral
reflectors ablate cornea 26 in a pattern comprising separate and
discrete areas of ablation shown in FIG. 6 or FIG. 8. Once beam
directing apparatus 10 is positioned, a test beam can be emitted to
test the alignment of the beams on cornea 26. Beam source 30 is
then operated to emit a radiant energy beam, such as a laser beam,
which travels along axis 24, encounters the central reflectors
12a-h, is split and radially reflected against peripheral
reflectors 14a-h and is then again radially reflected and focused
either onto the external surface of cornea 26 to simultaneously
make external incisions 17 or onto intrastromal areas of cornea 26
to simultaneously make intrastromal incisions 17a.
Embodiment of FIG. 3
With reference especially to FIG. 3, beam delivering system 10 can
have added to it an eye positioning device 32, coaxial with main
optical axis 24 and coupled to hub 18. Eye positioning apparatus 32
has a concave surface 34, preferably having a radius of curvature
the same as the average radius of curvature of a cornea, so that
cornea 26 can be pressed against concave surface 34 and steadied in
a fixed position during the eye operation. Eye positioning
apparatus 32 is coupled via a connecting stem 36 to hub 18.
Eye positioning device 32 is preferably constructed of material
which is transparent to the beam emitted by beam source 30 and
permits complete through transmission of the beams reflected from
the central and peripheral reflectors towards cornea 26.
Beam delivering apparatus 10 and eye positioning apparatus 32 can
be provided with a gas or fluid conduit system 40 for delivering
selected gases to the cornea 26 during ablation. Gas conduit system
40 includes a gas supply means 42 to supply gas along a tube 43 and
a conduit 44 mounted within one of the spokes 19. Conduit 44
communicates with an axial conduit 46 within eye positioning
apparatus 32 and axial conduit 46 communicates with a substantially
semihemispheric recess 48 defined by concave surface 34. Recess 48
communicates with conduit 46 and cornea 26 and has outlets 50 for
exhausting gases which have contacted cornea 26.
An inert gas such as argon can be supplied by gas conduit system 40
to contact cornea 26 and remove debris and other by-products of the
surgical operation. Additionally, a gas or liquid having a cold
temperature, such as, e.g., nitrous oxide, can be supplied by gas
conduit system 40 to bathe cornea 26 in a cool environment and
thereby lower the metabolic state of the cornea. Lowering the
metabolic state of cornea 26 enhances the ability of the cornea to
withstand traumatic insults from the beam.
To monitor the length and intensity of the beams directed onto the
external surface of cornea 26 or onto the intrastromal areas of
cornea 26 by apparatus 10, a plurality of linear detector arrays 58
can be installed. As seen in FIG. 3, apparatus 32 includes
frustoconical surface 60 adapted to partially reflect a small
portion (about 5%) of the beams directed towards cornea 26 by
peripheral reflectors. Surface 60 further reflects these small
portions of the beams against linear detectors 58 which are coupled
to a detector means 59 for determining the beam intensity
distribution and length. Preferably, three detectors 58 are used,
which are rigidly coupled to ring 21.
As seen in FIG. 3, the peripheral reflectors 14a'-h' are modified
from those shown in FIGS. 1 and 2 by having a curved reflective
surface 15' curved about an axis B which is perpendicular to axis
A. This curvature about axis B approximates the curvature of the
external surface of the cornea being ablated and provides a more
even ablation and beam intensity incident on the cornea. The radius
of curvature of the reflective surface 15' about axis B reduces in
the radially inward direction so the reflected line focus is
substantially coincident or parallel to with the outer surface of
the cornea. Reflective surface 15' is also curved and preferably
semi-cylindrical about axis A.
Beam delivering apparatus 10 of FIG. 3 therefore permits more
precision in the radial keratotomy procedure than existing systems
which interpose a mask between the beam source and the cornea.
Unlike the beams produced by the existing systems, each portion of
the beam reaching cornea 26 is substantially uniformly focused on
or in the cornea in a curved line focus. Thus, the distribution of
energy along the incision is substantially uniform and can
therefore be more precisely controlled.
Embodiment of FIG. 4
With reference now to the use of beam delivering apparatus 10 in an
eye lathing, or scanning, operation as shown in FIG. 4, apparatus
10 can be especially adapted for scanning an eye. In the embodiment
shown in FIG. 4, gas conduit system 40' is constructed with its
conduits 44' remote from spokes 20, in contrast to the embodiment
shown in FIG. 3 in which conduit 44 is formed within one of the
spokes 19. Ball bearing assembly 64 is provided at the connection
of connecting stem 36' and hub 18 so that the central and
peripheral reflectors can rotate relative to eye positioning device
32'.
Additionally, a drive assembly 66 having a drive motor 68 for
rotating a gear 70 is provided. Gear 70 meshes with a ring gear 72
which is rigidly connected to the sides of the peripheral
reflectors. Drive motor 68 is preferably a reversible, stepping
motor which allows for incremental rotation of central reflectors
12a-h together with peripheral reflectors 14a-h. Accordingly, the
radial lines focused on either the external or internal areas of
the cornea can be rotated 360.degree. or pivoted a few degrees in
either direction for removing selected portions of the cornea. For
example, a pair of radial lines can be focused onto the cornea and
pivoted approximately eight degrees from both sides of the X axis
to ablate a pair of wedge-shaped incisions 17" as seen in FIG. 12.
Of course, cornea 26 can be ablated to remove areas of the cornea
having a variety of configurations depending upon various factors
such as the number and position of lines, and the amount of
rotation.
To obtain the scanning pattern schematically shown in FIG. 7 as a
full lenticular ablation, drive motor 68 is operated to rotate gear
70 which, in turn, rotates ring 72 to rotate reflectors 12a-h and
14a-h about axis 24. Preferably, the reflectors are rotated at a
rate of approximately 200 revolutions per minute. However, rotation
speed is preferably selected for the given beam focusing width on
the cornea to remove material continuously over the cornea.
Conduits 44' can be formed from plates or tubes which are
transparent to the radiant energy beam so they do not interfere
with the beach. The scanning incision 17' is shown in FIG. 7 and is
in the form of a lenticular ablation in the shape of a positive,
negative or toxic lens. This ablation includes the full surface of
the cornea, although a central part can be omitted, thereby
providing an annular ablation. As used herein, "lenticular
ablation" means removing corneal material via laser photoablation
in the shape of an optical lens.
Embodiment of FIG. 5
To more precisely tailor the curved line focus of the beams
reflected from the peripheral reflectors so that corneas of
differing radii of curvature can be accommodated, each peripheral
reflector can be designed with a curved reflective surface whose
curvature varies along the length of the reflector along central
axis A. As shown in FIG. 5, peripheral reflector 14" has a concave
surface 71 varying from a smaller radius SR to a larger radius LR.
Accordingly, the beams reflected onto the external surface or onto
the intrastromal areas of the cornea 26 from reflectors 14" produce
radial incisions of desired curved line focus and thus intensity
therealong. Reflectors 14" accomplish similar result as reflectors
14a'-h' as seen in FIG. 3 but via a different reflector
configuration.
As shown in FIG. 1, the central reflectors can also be provided
with four inner and four outer alignment detectors 73 and 74 which
monitor the alignment of the reflectors with respect to the beam
incident thereon to allow adjustment of the laser beam to the
optical center thereof.
The beam delivering apparatus 10 of the present invention controls
and focuses the beam on the corneal surface or on intrastromal
areas. This is beneficial since the greater the amount of energy
radiated onto the cornea, the greater the risk that the cornea will
be damaged by overheating or, in the case of ultraviolet radiation,
by overshock.
The overall delivery system is quite compact and can be enclosed
between the laser 30 and gas conduit system 40' shown in FIG. 4.
This allows filling of the whole beam delivering system with a
neutral gas to minimize ozone build-up by ultraviolet
radiation.
As seen by comparing FIGS. 2 and 4, the arrangement of the central
and peripheral reflectors is the same for radial keratotomy and
lathing via scanning. The only difference in these procedures is
the rotation of the central and peripheral reflectors during
scanning.
Embodiment of FIG. 9
Referring now to the beam delivering apparatus 110 as shown in FIG.
9, apparatus 110 is substantially identical to the beach delivering
apparatus 10 of FIG. 3, except that peripheral reflectors 14a'-h'
have been replaced with peripheral reflectors 114a and 114b to
simultaneously forth two circumferentially curved incisions on
areas of a cornea. The circumferentially curved incisions can be
formed either on the external surface of a cornea or on
intrastromal areas of a cornea.
Specifically, beam delivering apparatus 110 as seen in FIG. 9
includes a pair of central reflectors 112a and 112b and an annular
assembly of peripheral reflectors 114a and 114b. Peripheral
reflectors 114a and 114b are rigidly coupled to a rim 116. Rim 116
is rigidly coupled to a hub 118 by radial spokes 119, axial rods
120 and a ring 121. Central reflectors 112a and 112b are coupled to
hub 118.
Beam delivering apparatus 110 is rotatably supported within a
support or frame 122 about a main optical axis 124 which passes
through the center of a cornea 126 of an eye. A laser beam source
130, such as a frequency modified YAG laser for ablating external
surface areas of the cornea or a frequency-doubled YAG laser for
ablating intrastromal areas of the cornea, is positioned to emit a
beam along axis 124 and against central reflectors 112a and 112b.
These reflectors split and reflect the beam onto peripheral
reflectors 114a and 114b which then focus and reflect the split
beams onto an area of cornea 126 in a curvilinear
configuration.
Referring now more specifically to the construction and orientation
of central reflectors 112a and 112b and peripheral reflectors 114a
and 114b for performing an operation to correct an astigmatism. A
pair of equal sized central reflectors 112a and 112b are provided.
While only two central reflectors are illustrated, the number of
central reflectors can be any even number more than two and less
than 16.
As shown in FIG. 9, two equally sized central reflectors 112a and
112b are rigidly coupled to one another along a pair of opposite
sides by a pair of connecting members 113 (only one shown) to form
a wedge-shaped mirror centered on axis 124. Each central reflector
112a and 112b is oriented to present a slanted, outwardly facing
flat surface to the beam emanating from beam source 130. The angle
of each surface is about 50.degree.-60.degree. to axis 124.
Each peripheral reflector 114a and 114b is associated with one of
the central reflectors 112a and 112b and is oriented so that its
reflective surface 115 intercepts the beam reflected radially,
outwardly by its associated central reflector. Additionally, each
peripheral reflector is oriented and constructed so as to reflect
the intercept beam axially and radially inward and to focus the
beam into line focus either onto the external surface of cornea 126
or onto an intrastromal area of the cornea. The line focus of each
beam onto cornea 126 is a curvilinear line which is preferably
circumferentially curved about the optical axis 124. Preferably,
the centers of the circumferentially curved lines focused on cornea
126 are located on optical axis 124.
The reflective surfaces of the central and peripheral reflectors
can be curved mirrors or other reflective material which focuses
the beam in a curvilinear configuration onto either an external or
internal areas of the cornea. For example, the peripheral
reflectors 114a and 114b as shown in FIG. 9 are holographic
elements or mirrors, which focus circumferential curved lines onto
areas of the cornea. Holographic elements or mirrors 114a and 114b
can be constructed with a flat reflective surface 115 having
different reflective indexes along reflective surface 115 so that a
variety of shapes and orientations of lines can be focused onto
either external or internal areas of the cornea, including
curvilinear lines and rectilinear lines.
As schematically shown in FIG. 10, a two circumferentially curved
incisions 117 are cut via photoablation in the external surface of
cornea 126 during an operation to correct an astigmatism.
Alternatively, two circumferentially curved, intrastromal incisions
117a can be cut via photoablation in intrastromal areas of cornea
126 during an operation to correct an astigmatism, as schematically
illustrated in FIG. 11.
Beam delivering apparatus 110 can be used to produce the external
or intrastromal incisions simultaneously. As seen in FIG. 9, each
central reflector 112a and 112b intercepts the beam and reflects
the beam towards its associated peripheral reflector 114a and 114b.
Central reflectors 112a and 112b are preferably rotatably coupled
to hub 118 via an axle 153 fitting into the hub 118 and a screw
adjustment assembly including three set screws 156 to lock the
reflectors relative to hub 118. Central reflectors 112a and 112b
can be moved as a single unit relative to hub 118 and the
adjustment screws 156 can then be operated to adjust and fix the
relative position of the central reflectors relative to the
peripheral reflectors.
The combination of central and peripheral reflectors including the
rim 116, hub 118, spokes 119, rods 120 and ring 121 are supported
for rotation relative to frame 122 via ball bearing assembly 138,
which is coupled to the frame and to rim 116. Thus, the angular
position of the reflectors relative to cornea 126 and axis 124 can
be varied. This allows angular placement as desired of either
external incisions 117 on the cornea or intrastromal incisions 117a
in the cornea.
The operation of beam delivering apparatus 110 during a simple
operation to correct an astigmatism is as follows. Cornea 126 is
immobilized by appropriate means and laser beam source 130 is
positioned to emit a beam along main optical axis 124, which passes
through the center of cornea 126. Beam directing apparatus 110 is
positioned between beam source 130 and cornea 126 and is
appropriately spaced from cornea 126 so that the beams reflected by
the central and peripheral reflectors ablate cornea 126 in a
pattern comprising separate and discrete areas of ablation shown in
FIG. 10 or FIG. 11. Once beam directing apparatus 110 is
positioned, a test beam can be emitted to test the alignment of the
beams on cornea 126. Beam source 130 is then operated to emit a
radiant energy beam, such as a laser beam, which travels along axis
124, encounters the central reflectors 112a and 112b, is split and
radially reflected against peripheral reflectors 114a and 114b and
is then again radially reflected and focused either onto the
external surface of cornea 126 to simultaneously make external
incisions 117 or onto intrastromal areas of cornea 126 to
simultaneously make intrastromal incisions 117a.
A drive assembly 166 having a drive motor 168 for rotating a gear
170 is provided. Gear 170 meshes with a ring gear 172 which is
rigidly connected to the sides of the peripheral reflectors. Drive
motor 168 is preferably a reversible, stepping motor which allows
for incremental rotation of central reflectors 112a and 112b
together with peripheral reflectors 114a and 114b. Accordingly, the
circumferentially curved lines, which are focused on either
external or internal areas of the cornea, can be rotated
360.degree. or pivoted a few degrees to remove selected portions of
the cornea.
It should be apparent to those skilled in the art that a plurality
of curvilinear lines can be focused onto the cornea at various
positions to ablate the cornea as required to correct the patient's
vision.
Beam delivering apparatus 110 and eye positioning apparatus 132 can
be provided with a gas or fluid conduit system 140 for delivering
selected gases to the cornea 126 during ablation. Gas conduit
system 140 includes a gas supply means 142 to supply gas along a
tube 143 and a conduit 144 mounted within one of the spokes 119.
Conduit 144 communicates with an axial conduit 146 within eye
positioning apparatus 132 and axial conduit 146 communicates with a
substantially semihemispheric recess 148 defined by concave surface
134. Recess 148 communicates with conduit 146 and cornea 126 and
has outlets 150 for exhausting gases which have contacted cornea
126.
An inert gas such as argon can be supplied by gas conduit system
140 to contact cornea 126 and remove debris and other by-products
of the surgical operation. Additionally, a gas or liquid having a
cold temperature, such as, e.g., nitrous oxide, can be supplied by
gas conduit system 140 to bathe cornea 126 in a cool environment
and thereby lower the metabolic state of the cornea. Lowering the
metabolic state of cornea 126 enhances the ability of the cornea to
withstand traumatic insults from the beam.
While various advantageous embodiments have been chosen to
illustrate the invention, it will be understood by those skilled in
the art that various changes and modifications can be made therein
without departing from the scope of the invention as defined in the
appended claims.
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